US Patent 7694768 Snowmobile drive assembly

A snowmobile rear suspension is shown comprised of a linear force element (LFE) positioned outside the envelope of the snowmobile endless track. The snowmobile frame includes a chassis mounted to a tunnel, where the chassis includes a central mounting bracket. The LFE is attached at one end to the bracket and at the other end to a bell crank. The bell crank is operatively connected to the slide rails. When the slide rails collapse in normal operation, the bell crank strokes the LFE, and the suspension is progressive throughout the range. The suspension includes front pivot links which are connected to the tunnel coaxially with a drive shaft.